Sensitivity to impact and friction

Montan Wax (Lignite wax). White, hard earth wax crude product, dark brown, mp 80—90°. Obtained by countercurrent extrn of lignite. Sol in CCI4, benz chlf insol in w. It is combustible nontoxic. Has been used extensively in Ger for coating particles of expls such as PETN RDX, in order to reduce their sensitivity to impact and friction Ref CondChemDict (1971), 595-R... 

Norris Powder. A low-freezing mining expl invented in 1901 by an American, Norris. It was much less sensitive to impact and friction than contemporary Dynamites. It contained NG 70, mononitrobenzene 15, and Huile empyroma-tique 15%. The latter ingredient consisted of ail oily substance obtained on distn of wood tar. 

If an expl is intended for use in primers, then its brisance and power may be lower than for groups (1), (2) and (3), but it should possess low sensitivity to impact and friction and should produce a hot flame in order to ignite a charge of proplnt or a deiay train... 

Torpedo friction test. A test of sensitiveness to impact and friction (see p. 70). 

The endothermic nitride is susceptible to explosive decomposition on friction, shock or heating above 100°C [1], Explosion is violent if initiated by a detonator [2], Sensitivity toward heat and shock increases with purity. Preparative precautions have been detailed [3], and further improvements in safety procedures and handling described [4], An improved plasma pyrolysis procedure to produce poly (sulfur nitride) films has been described [5], Light crushing of a small sample of impure material (m.p. below 160°C, supposedly of relatively low sensitivity) prior to purification by sublimation led to a violent explosion [6] and a restatement of the need [4] for adequate precautions. Explosive sensitivity tests have shown it to be more sensitive to impact and friction than is lead azide, used in detonators. Spark-sensitivity is, however, relatively low [7],... 

A substance or mixture is potentially capable of deflagration if it has a AHd greater than 250 cal/g (-1000 J/g), a "yes" in Box 8. Deflagration tests (Box 7) then should be carried out as well as tests for sensitivity to impact and friction. 

The thermochemical evaluation of the reactants is the place to start, as discussed in Chapter 2. If the potential energy release is 250 cal/g of substance (1000 J/g) or more, it is necessary to determine initiation properties, such as a sensitivity to impact and friction. Thermochemical evaluation of reaction... 

Mercury fulminate (C2N202Hg) is one of the most important primary explosives. It is usually found in the form of a gray powder, is sensitive to impact and friction, and is easily detonated by sparks and flames. It is desensitized by the addition of water, but is very sensitive to sunlight. It reacts with metals in moist environments. It is created by treating a solution of mercuric nitrate with alcohol in nitric acid. Its most important explosive property is that it easily detonates after initiation.10... 

Oxidative nitration avoids the isolation of em-nitronitronate salts, which are often unstable explosives with a high sensitivity to impact and friction. 

Similarly, 5-picrylamino-l,2,3,4-tetrazole (PAT) (116) " " and 5,5 -styphnylamino-1,2,3,4-tetrazole (SAT) (117) " have been synthesized by condensing picryl chloride and styphnyl chloride with 5-amino-l,2,3,4-tetrazole in methanol respectively. A comparison of thermal and explosive properties of newly synthesized PAT (calculated VOD 8126 m/s) and SAT (calculated VOD 8602 m/s) reveals that PAT is more thermally stable than SAT but more sensitive to impact and friction. " ... 

The energetic nature of the N-NO2 group means that At-nitro-based explosives are some of the most powerful explosives available and these have largely superseded aromatic C-nitro compounds for military applications. Many nitramines exhibit high brisance and high chemical stability in combination with a favourable low sensitivity to impact and friction compared to nitrate ester explosives of similar power. 

Hexotonal has been manufd by AB Bofors for use as a cast filling at d 1.68-1.74. Its sensitivity to impact and friction is moderated by an addn of wax, its sensitivity to initiation is comparable to that of Hexotol, but bursting effect and fragmentation power are higher (Ref 3, p 203)... 

Haishokuyaku (Gray Powder). A dark-gray, non-toxic exp cornpni No 1 Mixture con sisted of Amm Perchlorate 76.9, RDX 17.0, silicon carbide 1.3 paraffin 4.8% relative Power Brisance greater than for PA, but it is less sensitive to impact and friction. Used in Army Standard Demolition Blocks No 2 Mixture consisted of Amm Perchlorate 48, GuN (Guanidine Nitrate) 20, RDX 25 paraffin 5%. It was a commercial mining expl, and also used in Army Demolition Blocks (Rsf 1 p 28 R.ef 5, pp 365-66)... 

Kinetite is very insensitive to heat, but too sensitive to impact and friction. It was not stable in storage, and sometimes expld spontaneously with no apparent cause Refs 1) Daniel (1902), 392 2) Colver... 

Its sensitiveness to impact and friction is classed as too low to require classification as a Class 1 Explosive... 

The performance of the illuminating formulations is assessed by various parameters such as burning rate, luminosity and luminous efficiency. In addition to performance, some other important characteristics such as sensitivity to impact and friction, ignition temperature, mechanical properties and luminosity are also... 

As regards explosive strength, nitramines occupy a position midway between nitro compounds and nitric esters. They also hold a central position regarding other properties, such as chemical stability and sensitiveness to impact and friction. 

Sodium azide (see above, p. 189 and Table 36) can be decomposed on heating but it is of low sensitiveness to impact or friction and is not listed as an explosive in transport regulations. According to Gunther et al. [138] rubidium azide is much more sensitive to impact and friction than sodium azide. Gunther believes this to be due to the fact that the radius of the orbit of nitrogen atoms in rubidium azide is much shorter than that in sodium azide. 

Trinitrotriazidobenzene is less sensitive to impact and friction than mercury fulminate. 

This substance is prepared by the action of a hot solution of lead nitrate on a solution of sodium dinitroresorcinate. The lead salt is precipitated as the solution cools. Lead dinitroresorcinate ignites from a direct flame readily and burns with great velocity. Its initiating action is weaker than that of lead styphnate and it is less sensitive to impact and friction than styphnate. It has therefore recently found application as a component of cap compositions. It is valuable because it is safer to handle than styphnate. The preparation of dinitroresorcinol is discussed in Vol. I, p. 536. 

Care should be taken that cuprous acetylide is not contaminated with cupric acetylide which may occur if the cuprous chloride used for the reaction contains cupric salt. This is of importance since cupric acetylide is unstable and explodes on heating even between 50 and 70°C. It is also more sensitive to impact and friction than cuprous acetylide. The pure cupric acetylide is black or brown. 

It must be borne in mind that generally aromatic nitro compounds are not highly sensitive to impact and friction, but become more sensitive at elevated temperatures as they melt (changes in the sensitiveness of TNT are discussed in Vol. I, p. 319). If, therefore, a mechanical device is used for the preparation of mixtures by melting, its construction should be such as to exclude any possibility of friction or impact. It is probably best to use a converter heated with steam or water jackets and fitted with a stirrer that can be lifted out by a special arrangement. After the stirrer has been removed, the contents are poured out by tilting the vessel. 

The first attempts to substitute potassium chlorate for potassium nitrate undertaken by Berthollet [32], who discovered potassium chlorate, were unsuccessful. It was immediately evident that a mixture of potassium chlorate, sulphur and charcoal was exceptionally sensitive to impact and friction, and was therefore too dangerous to manufacture. The removal of sulphur from the mixture did not increase safety and thus the powder has never found practical application. 

Blackpowder is highly sensitive to impact and friction. It explodes when struck by a 2 kg weight falling from 70-100 cm. Its ignition temperature is 300°C. A sack filled with blackpowder takes fire when penetrated by a rifle shot. 

These mixtures, however, brought no new advantages and did not fully meet requirements with regard to safety in gassy and dusty mines, sensitiveness to impact and friction and mining efficiency. In addition, perchlorate explosives, like chlorate ones, have the defect that under certain conditions they do not detonate, but burn out in the shothole, which may lead to a catastrophic fire or explosion. Perchlorate explosives were then withdrawn from coal work after World War I and restricted exclusively to rock work. Japan seems to be the only country where some perchlorate explosives are accepted as permitted explosives (see p. 474). 

A disadvantage of mixtures of liquid oxygen with combustible substances lies in their high sensitiveness to impact and friction. This property depends largely on the composition of the combustible material used. Oxyliquits containing sawdust show the lowest sensitiveness, while those containing hydrocarbons (e.g. naphthalene) pitch or petrol are more sensitive. 

Smokeless powders have low sensitiveness to impact and friction. They do not ignite when hit by rifle bullets and are thus fairly safe to handle in war-time. Nevertheless there have been accidents caused by the sudden ignition of nitrocellulose powder brought about by the violent friction between the sharp edge of a heavy bin and powder scattered on the floor. 

Powder grains are sensitive to impact and friction. This is due to the sensitiveness of the main ingredients, nitrocellulose and nitroglycerine. The sensitiveness of these compounds was discussed in Vol. II. 

It should be bom in mind that the sensitiveness to impact and friction increases with temperature. Hence any handling of warm powder (e.g. immediately after drying) should be avoided. >... 

As a rule, a small quantity of DPEHN present in PETN improves its stability and sensitivity to impact and friction, while large quantities decrease the stability slightly (Ref 2)... 

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